Nanoplastic ingestion causes neurological deficits

Microplastics, or plastic particulates measuring less than five micrometers, are a growing environmental concern. These particulates disrupt reproduction, immune cell and microbiome composition in the gut, and neural and endocrine function in aquatic species and laboratory animals.1-4 Now, a new study published in Cell Reports suggests that the smaller the plastic, the greater the problem.

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Recent studies have shown that inflammatory responses in the intestines affect the brain, so Wang and his team next assessed the gut-brain axis. After two months of daily ingestion of nanoplastics at the estimated human consumption dose, nanoplastic-exposed mice exhibited reduced cognition and short-term memory as assessed by standard neurological assessments such as the open-field test, novel object recognition assay, and the Morris water maze. These plastic-fed mice also had more activated microglia and astrocytes as well as Th17-differentiated T cells than nontreated mice.

Wang and his colleagues also observed elevated IL-1β in the brains of plastic-fed mice, but did not find IL-1β-producing cells in the brain, which suggested that these effects resulted from IL-1β-producing macrophages in the gut. “All these changes associated with brain function damage,” Wang said.